Method of forming a metal valve seat

ABSTRACT

A metal valve seat and method of forming the same which includes providing an annulus having a thick annular body and a thin neck defining a sealing end of the body. After the annulus has been mounted in the valve body, a ball is placed on the neck and an impact force is applied to the ball thereby deforming the neck and forming an annular concave sealing surface which conforms to the contacted curvature of the ball.

United States Patent 1 1 5/l89l Bavier ..29/l56.7 A X Freiheit 1451 1 June 5, 1973 54 METHOD OF FORMING A METAL 1,709,807 4 1929 lurnis ..29/l56.7 A x VALVE SEAT 1,960,385 5 1934 Lofgren'... ..29/l56.7 A v 2,121,464 6/1938 Zagnrski ...25l/l67 [75] Inventor: Frederick E. Freiheit, East Lansing, 'Mich- Primary Examiner-Charles W. Lanham [73] Assignee: FMC Corporation; San Jose, Calif. Assistant -Q m 1 I Attorney-F. W. Anderson, C. E. Trrpp and A. J. [22] Fried: Dec. 15, 1970 Moore 21 A 1. N0.: 98 221 I 1 Pp 57 ABSTRACT 52] 11.5. (:1. ..29 /157.1 R 29/l56.7 A 251/365 A metal valve seat and fmming the a 511 1111. C1. 11 211 1 20 B211 29/00 which includes Pmviding having a thick 58 Field of Search; 29 1571 156 7 annular and a thin defining Sealing end v A 7 the body. After the annulus has been mounted in the I valve body, a ball is placed on the neck and an impact I 56] References Cited force is applied to the ball thereby deforming the neck v p and forming an annular concave sealing surface which UNITED ST S NTS conforms to the contacted curvature of the ball.

6 Claims, 5 Drawin Figures so 28 6 FIB--1 -AGENT BACKGROUND OF THE INVENTION l. Field of the Invention This invention pertains to the valve art and more particularly relates to an improved valve seat for a ball valve and method of making the same.

2. Description of Prior Art A valve seat for a ball valve of the type disclosed herein is illustrated in U.S. Pat. No. 2,362,946 which issued to I-LC. Stockdale on Nov. 14, 1944 and is assigned to the assignees predecessor corporation. This prior art valve seat was used in a spray gun handling abrasive spray fluids, and accordingly, is made from hard abrasive resisting material such as stainless steel which is difficult to machine. Because of this difficulty in accurately machining the hard material, and because of the damage which frequently resulted when pressing the valve seat into the valve body after the machining operation was completed, leakage frequently'occurred between the ball and the valve seat of this prior art device.

SUMMARY OF THE INVENTION A leak-proof seal is formed between a sealing ball and the metal valve seat of the present invention by forming a relatively thin neck on the valve seat at the sealing end thereof. An annular concave seal is formed on the inner edge of the sealing end of the neck, after the valve seat has first been fitted in fluid tight engagement in the body of the valve, by applying an impact force to the neck with a ball which is the same size as thesealing ball.

An object of the invention is to provide an improved valve seat having an annular concave sealing surface.

Another object is to provide an improved method of forming an annular concave sealing surface in a metal valve seat.

BRIEF DESCRIPTION OF THE DRAWINGS 7 FIG. 1 is a central vertical section through a spray gun employing the valve seat of the present invention.

FIG. 2 is an enlarged vertical central section through a prior art valve seat.

FIG. 3 is an enlarged vertical section of the valve seat of the present invention illustrating the seat after it has been pressed into the body of the valve but prior to having an impact force applied thereto by a seat forming ball.

FIG. 4 is a section similar to FIG. 3 but illustrating the valve seat after'an impact force has been applied thereto.

FIG. 5 is a vertical central section through the completed ball valve seat, the location of the sealing ball being shown in phantom lines when in the sealing position.

DESCRIPTION OF PREFERRED EMBODIMENT The valve seat (FIGS. 1 and 3-5) of the present invention is illustrated as being seated in a spray gun 12 of conventional design. The valve seat 10 is pressed into a bore 14 in'the housing or body 16 of the spray gun 12 to provide a fluid tight seal between the outer walls of the valve seat and the housing 16. The housing 16 includes an inlet passage 18 (FIG. 1) connected to a supply of fluid under high pressure, and a discharge passage 20. Aspray nozzle 22 of conventional design is connected to the discharge passage of the housing 16 by a tube 24.

The valve seat 10 cooperates with a sealing ball 26 to define a ball valve 28. A spring 30 is disposed between the ball 26 and a cap 32 screwed into the housing and normally urges the ball 26 into sealing engagement with the valve seat 10. A valve stem 34 is slidably received in a packing gland 36 and has one end abutting the sealing ball 26 and the other end contacting a trigger 38.

The trigger 38 is mounted for swinging movement by two pins 40 secured to a hollow handle 42 of the housing 16 and passing through slots 44 in the trigger. A hooked latch arm 46 is pivoted about a pin 48 secured to the trigger and is urged in a clockwise direction by a spring 50. If it is desired to latch the sealing ball 26 in an open position, the operator merely pulls the trigger 38 back and pivots the latch arm 47 counterclockwise so that the hooked end 52 of the latch arm 46 will engage a pin 54 in the handle 42. when the trigger 38 is allowed to move a short distance forward.

A valve seat 60 of the type used in the prior art is illustrated in FIG. 2 and includes an annulus 62 having its inner sealing edge machined to form a generally frusto-conical valve seta 64. It was determined that such a sealing surface was subject to leakage asmachined because it could not be held to close tolerances. It was also determined that after attempts were made to conform the frusto-conical sealing surface to the shape of its sealing ball by applying impact forces to the ball, that such attempts were ineffective to provide a leak-proof seal. It is believed that the stiffness of the thick upper portion of the prior art valve seat 60 prevented the annulus 62 from deforming sufficiently to conform to the curvature of the associated sealing ball.

In accordance with the present invention, the annular valve seat 10 (FIGS. 3 to 5) includes a thick base 66 formed integrally with a neck 68 having a wall thickness approximately one-half that of the base 66. The neck 68 is flared into the wide base 66 by an annular arcuately curved outer surface 69. The base 66 includes a seating end 70 which may have its outer edge 72 chamfered, and the neck includes a sealing end 74 having an internal circumferential edge 76 which, prior to forming a sealing surface 78 thereon, is equal in diameter to the bore 80 through the valve seat '10.

Prior to forming the circumferential edge 76 (FIG. 3) into the annular concave sealing surface 78 (FIGS. 4 and 5), the valve seat 10 is preferably press fitted into the bore 14 of the housing 16. Any suitable tool may be used for this purpose. For example, a fluid operated pressure applying head 82 may be used, which head has surfaces 84 adjacent its periphery that conform in shape to the sealing end 74 of the valve seat 10. Thus, the head 82 is lowered until the surface 84 engages the sealing end 74 of the. valve seat and then applies sufficient force to move the valve seat 10 to the position indicated in FIG. 3 wherein a fluid tight relationship exists between the thick base 66 and the bore 14 of the gun housing 16.

After the valve seat 10 has been seated in the housing 16, the pressure applying head 82 is raised and a ball 26 is placed on the circumferential edge 76. A curved surface 86 of the pressure applying head 82 is then rapidly moved against the ball 26 to impart an impact force to the ball and consequently to the edge 76 thus partially bending the neck and partially deforming the metal edge 76 by cold forging to conform to the shape of the contacted portion of the ball as indicated in FIGS. 4 and 5 forming the annular concave sealing surface 78.

Although the sealing ball 26 has been illustrated as being used both for the sealing function and the seat forming function, it will be understood that a separate seat forming ball or tool having a spherical segment which is identical in diameter to the sealing ball 26 is preferably used to form the sealing surfaces 78 on many valve seats. It will also be understood that in the claims, the term metal ball for forming the concave sealing surface is to be construed as being broad enough to cover any tool having a spherical segment formed thereon which has a diameter at its seat contacting surface equal to that of the sealing ball 26.

It will also be understood that the valve seats may be pressed into the spray gun housings as above described, and that the impact force may be applied to the ball by another tool at a later time such as by a hand operated hammer. Thus, a purchaser of the spray gun may reface defective .or worn sealing surfaces at any time by merely removing the cap 32 (FIG. 4) from the gun and applying an impact force to the ball 26 by means of a hammer with the aid of a punch or the like. It will further be understood that the use of the valve seat is not intended to be limited to use only in spray guns but may also be used in other types of valve housings.

From the foregoing description it will be apparent that the metal valve seat of the present invention and the method of making the same contemplates reducing the thickness of a portion of the valve-seat and, after first mounting the seat in its valve housing, applying an semblyso as to partially bend and partially deform the metal to form an annular concave valve seat.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

What I claim is:

l. A method of forming a metal valve seat for a ball valve comprising the steps of forming an annulus having a seating end and a sealing end, reducing the thick ness of the annulus at the sealing end, placing a metal ball against the inner surface of the annulus at the sealing end, and applying a force to the ball normally of the plane of said sealing end sufficient to deform the reduced thickness portion of the annulus to provide a sealing surface conforming in shape to that of the contacted surface of the ball.

2. A method according to claim 1 and additionally comprising the step of mounting the seating end of the annulus in fluid tight relation with a valve body prior to deforming the seating end thereof.

3. A method according to claim 2 wherein the mounting of the annulus is performed by a press fitting operation.

4. A method according to claim 1 wherein the deforming force applied to the ball is an impact force which partially bends and partially cold forges the sealing surface. v

5. A method according to claim 1 wherein the thick ness of the sealing end is reduced by reducing the outside diameter of the annulus of the sealing end thereof.

6. A method according to claim 2 wherein the reduction' in the diameter provides an annular neck adjacent the sealing end of the annulus which is approximately one-half as thick as the body of the annulus.

. ill

@2253? UNITED STATES PATENT OFFICE v RTIFICATE OF CORRECTION Patent No. 3'736,640 Dated June 5, 1973 Inventor) FREDERICK E. FREIHEIT It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 17, change "47" to --46---.

C01. 2, line 24, change "seta" to --seat--.

Signed and sealed this 4th day of February 1975.

(SEAL) Attest:

McCOY M. GIBSON JR. Arresting Officer C. MARSHALL DANN Commissiqner of Patents 

1. A method of forming a metal valve seat for a ball valve comprising the steps of forming an annulus having a seating end and a sealing end, reducing the thickness of the annulus at the sealing end, placing a metal ball against the inner surface of the annulus at the sealing end, and applying a force to the ball normally of the plane of said sealing end sufficient to deform the reduced thickness portion of the annulus to provide a sealing surface conforming in shape to that of the contacted surface of the ball.
 2. A method according to claim 1 and additionally comprising the step of mounting the seating end of the annulus in fluid tight relation with a valve body prior to deforming the seating end thereof.
 3. A method according to claim 2 wherein the mounting of the annulus is performed by a press fitting operation.
 4. A method according to claim 1 wherein the deforming force applied to the ball is an impact force which partially bends and partially cold forges the sealing surface.
 5. A method according to claim 1 wherein the thickness of the sealing end is reduced by reducing the outside diameter of the annulus of the sealing end thereof.
 6. A method according to claim 2 wherein the reduction in the diameter provides an annular neck adjacent the sealing end of the annulus which is approximately one-half as thick as the body of the annulus. 